Internet Engineering Task Force                             N. Kuhn, Ed.
Internet-Draft                                                      CNES
Intended status: Informational                            E. Lochin, Ed.
Expires: July 7, 2019                                       ISAE-SUPAERO
                                                             Jan 3, 2019


                     Network coding and satellites
             draft-irtf-nwcrg-network-coding-satellites-04

Abstract

   This memo details a multi-gateway satellite system to identify
   multiple opportunities on how coding techniques could be deployed at
   a wider scale.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on July 7, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Glossary  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  A note on satellite topology  . . . . . . . . . . . . . . . .   4
   3.  Actual deployment of reliability schemes in satellite systems   6
   4.  Details on the use cases  . . . . . . . . . . . . . . . . . .   7
     4.1.  Two-way relay channel mode  . . . . . . . . . . . . . . .   7
     4.2.  Reliable multicast  . . . . . . . . . . . . . . . . . . .   8
     4.3.  Hybrid access . . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Dealing with varying capacity . . . . . . . . . . . . . .   9
     4.5.  Improving the gateway handovers . . . . . . . . . . . . .  10
   5.  Research challenges . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  Towards an increased deployability in SATCOM systems  . .  11
     5.2.  Interaction with virtualization . . . . . . . . . . . . .  11
     5.3.  Delay/Disruption Tolerant Networks  . . . . . . . . . . .  12
   6.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  12
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   10. Informative References  . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Guaranteeing both physical-layer robustness and efficient usage of
   the radio resource has been in the core design of SATellite
   COMmunication (SATCOM) systems.  The trade-off often resided in how
   much redundancy a system adds to cope from link impairments, without
   reducing the good-put when the channel quality is high.  There is
   usually enough redundancy to guarantee a Quasi-Error Free
   transmission.  However, physical layer reliability mechanisms may not
   recover transmission losses (e.g. with a mobile user) and layer 2 (or
   above) re-transmissions induce 500 ms one-way delay with a
   geostationary satellite.  Further exploiting coding schemes at higher
   OSI-layers is an opportunity for releasing constraints on the
   physical layer in such cases and improving the performance of SATCOM
   systems.

   We have noticed an active research activity on coding and SATCOM in
   the past.  That being said, not much has actually made it to
   industrial developments.  In this context, this document aims at
   identifying opportunities for further usage of coding in these
   systems.

   This document follows the taxonomy of coding techniques for efficient
   network communications [RFC8406].




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1.1.  Glossary

   The glossary of this memo extends the glossary of the taxonomy
   document [RFC8406] as follows:

   o  ACM : Adaptative Coding and Modulation;

   o  BBFRAME: Base-Band FRAME - satellite communication layer 2
      encapsulation work as follows: (1) each layer 3 packet is
      encapsulated with a Generic Stream Encapsulation (GSE) mechanism,
      (2) GSE packets are gathered to create BBFRAMEs, (3) BBFRAMEs
      contain information related to how they have to be modulated (4)
      BBFRAMEs are forwarded to the physical-layer;

   o  CPE: Customer Premise Equipment;

   o  COM: COMmunication;

   o  DSL: Digital Subscriber Line;

   o  DTN: Delay/Disruption Tolerant Network;

   o  ETSI: European Telecommunications Standards Institute;

   o  FEC: Forward Erasure Correction;

   o  FLUTE: File Delivery over Unidirectional Transport;

   o  IoT: Internet of Things;

   o  LTE: Long Term Evolution;

   o  NFV: Network Function Virtualization;

   o  NORM: NACK-Oriented Reliable Multicast;

   o  PEP: Performance Enhanced Proxy [RFC3135] - a typical PEP for
      satellite communications include compression, caching and TCP
      acceleration;

   o  PLFRAME: Physical Layer FRAME - modulated version of a BBFRAME
      with additional information (e.g. related to synchronization);

   o  QEF: Quasi-Error-Free;

   o  QoE: Quality-of-Experience;

   o  QoS: Quality-of-Service;



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   o  SAT: SATellite;

   o  SATCOM: generic term related to all kind of SATellite
      COMmunication systems;

   o  VNF: Virtual Network Function.

2.  A note on satellite topology

   This section describes the components in satellite system that lays
   on SATCOM systems dedicated to broadband Internet access that follows
   the DVB standards.  A high-level description of a multi-gateway
   satellites network is provided.  There are multiple SATCOM systems,
   such as those dedicated to broadcasting TV or to IoT applications:
   depending on the purpose of the SATCOM system, ground segments are
   specific.  In this context, the increase of the available capacity
   that is carried out to end users and reliability requirements lead to
   multiple gateways for one unique satellite platform.

   In this context, Figure 1 shows an example of a multi-gateway
   satellite system.  In a multi-gateway system, some elements may be
   centralized and/or gathered: the relevance of one approach compared
   to another depends on the deployment scenario.  More information on
   these discussions and a generic SATCOM ground segment architecture
   for a bi-directional Internet access can be found in [SAT2017].

   Some functional blocks aggregate the traffic of multiple users.
   Coding schemes could be applied on both single and aggregated
   traffic.






















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   +---------------------+
   | application servers |
   +---------------------+
          ^     ^
          | ... |
          -----------------------------------
          v     v   v             v   v     v
   +------------------+         +------------------+
   | network function |         | network function |
   | (firewall, PEP)  |         | (firewall, PEP)  |
   +------------------+         +------------------+
       ^     ^                        ^        ^
       | ... | IP packets             |  ...   |
       v     v                        v        v
   +------------------+         +------------------+
   | access gateway   |         | access gateway   |
   +------------------+         +------------------+
          ^                                 ^
          | BBFRAME                         |
          v                                 v
   +------------------+         +------------------+
   | physical gateway |         | physical gateway |
   +------------------+         +------------------+
          ^                                 ^
          | PLFRAME                         |
          v                                 v
   +------------------+         +------------------+
   | outdoor unit     |         | outdoor unit     |
   +------------------+         +------------------+
          ^                                 ^
          | satellite link                  |
          v                                 v
   +------------------+         +------------------+
   | sat terminals    |         | sat terminals    |
   +------------------+         +------------------+
          ^     ^                  ^     ^
          | ... |                  | ... |
          v     v                  v     v
   +------------------+         +------------------+
   | end user         |         | end user         |
   +------------------+         +------------------+

    Figure 1: Data plane functions in a generic satellite multi-gateway
                                  system







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3.  Actual deployment of reliability schemes in satellite systems

   The notations used in this section are based on the taxonomy document
   [RFC8406]: End-to-End Coding (E2E), Network Coding (NC), Intra-Flow
   Coding (IntraF), Inter-Flow Coding (InterF), Single-Path Coding (SPC)
   and Multi-Path Coding (MPC).  This document refers to coding as both
   End-to-End Coding and Network Coding, to cover cases where where
   recoding operation at intermediate nodes are or not.  From the UDP/IP
   packetization to the channel coding, link layer coding is required so
   that the physical-layer knows what coding scheme to use.  Following
   the taxonomy document [RFC8406], channel and link codings are
   gathered in the PHY layer coding and are out of the scope of this
   document.

   Figure 2 presents the status of the reliability schemes deployment in
   satellite systems.

   o  X1 embodies the source coding that could be used at application
      level for instance within QUIC or other video streaming
      applications.  This is not specific to SATCOM systems since such
      deployment can be relevant for broadband Internet access
      discussions.

   o  X2 embodies the physical-layer, applied to the PLFRAME, to
      optimize the satellite capacity usage.  At the physical layer, FEC
      mechanisms can be exploited.

   +------+-------+---------+---------------+-------+
   |      | Upper | Middle  | Communication layers  |
   |      | Appl. | ware    |                       |
   +      +-------+---------+---------------+-------+
   |      |Source | Network | Packetization | PHY   |
   |      |coding | AL-FEC  | UDP/IP        | layer |
   +------+-------+---------+---------------+-------+
   |E2E   |   X1  |         |               |       |
   |NC    |       |         |               |       |
   |IntraF|   X1  |         |               |       |
   |InterF|       |         |               |   X2  |
   |SPC   |   X1  |         |               |   X2  |
   |MPC   |       |         |               |       |
   +------+-------+---------+---------------+-------+

        Figure 2: Reliability schemes in current satellite systems

   Reliability is an inherent part of the physical-layer and usually
   achieved by using coding techniques.  Based on public information,
   coding does not seem to be widely used at higher layers.




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4.  Details on the use cases

   This section details use-cases where coding schemes could improve the
   overall performance of a SATCOM system (e.g. considering a more
   efficient usage of the satellite resource, delivery delay, delivery
   ratio).

   It is worth noting that these use-cases mostly focus on the
   middleware and packetization UDP/IP of Figure 2.  There are already
   lots of recovery mechanisms at the physical-layer in currently
   deployed systems while E2E source coding is done at the application
   level.  In a multi-gateway SATCOM Internet access, the deployment
   opportunities are more relevant in specific SATCOM components such as
   the "network function" block or the "access gateway" of Figure 1.

4.1.  Two-way relay channel mode

   This use-case considers a two-way communication between end users,
   through a satellite link.  Figure 3 proposes an illustration of this
   scenario.

   Satellite terminal A sends a flow A and satellite terminal B sends a
   flow B to a NC server.  The NC server sends a combination of both
   terminal flows.  This results in non-negligible capacity savings and
   has been demonstrated [ASMS2010].  Moreover, with On-Board Processing
   satellite payloads, the coding operations could be done at the
   satellite level.

   -X}-   : traffic from satellite terminal X to the server
   ={X+Y= : traffic from X and Y combined sent from
               the server to terminals X and Y

   +-----------+        +-----+
   |Sat term A |--A}-+  |     |
   +-----------+     |  |     |      +---------+      +------+
       ^^            +--|     |--A}--|         |--A}--|      |
       ||               | SAT |--B}--| Gateway |--B}--|Server|
       ===={A+B=========|     |={A+B=|         |={A+B=|      |
       ||               |     |      +---------+      +------+
       vv            +--|     |
   +-----------+     |  |     |
   |Sat term B |--B}-+  |     |
   +-----------+        +-----+

     Figure 3: Network architecture for two way relay channel with NC






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4.2.  Reliable multicast

   Using multicast servers is a way to better exploit the satellite
   broadcast capabilities.  This approach is proposed in the SHINE ESA
   project [I-D.vazquez-nfvrg-netcod-function-virtualization] [SHINE].
   This use-case considers adding redundancy to a multicast flow
   depending on what has been received by different end-users, resulting
   in non-negligible scarce resource saving.  We propose an illustration
   for this scenario in Figure 4.

   A multicast flow (M) is forwarded to both satellite terminals A and
   B.  However packet Ni (resp.  Nj) get lost at terminal A (resp.  B),
   and terminal A (resp.  B) returns a negative acknowledgment Li (resp.
   Lj), indicating that the packet is missing.  Then either the access
   gateway or the multicast server includes a repair packet (rather than
   the individual Ni and Nj packets) in the multicast flow to let both
   terminals recover from losses.  This could be achieved by using NACK-
   Oriented Reliable Multicast (NORM) [RFC5740] in situations where a
   feedback link is available, or File Delivery over Unidirectional
   Transport (FLUTE) [RFC6726] otherwise.  Note that both NORM and FLUTE
   are limited to block coding, none of them supporting sliding window
   encoding schemes [RFC8406].

   -Li}- : packet indicating the loss of packet i of a multicast flow M
   ={M== : multicast flow including the missing packets

   +-----------+       +-----+
   |Sat term A |-Li}-+ |     |
   +-----------+     | |     |      +---------+  +------+
       ^^            +-|     |-Li}--|         |  |Multi |
       ||              | SAT |-Lj}--| Gateway |--|Cast  |
       ===={M==========|     |={M===|         |  |Server|
       ||              |     |      +---------+  +------+
       vv            +-|     |
   +-----------+     | |     |
   |Sat term B |-Lj}-+ |     |
   +-----------+       +-----+

      Figure 4: Network architecture for a reliable multicast with NC

4.3.  Hybrid access

   This use-case considers the use of multiple path management with
   coding at the transport level to increase the reliability and/or the
   total capacity (using multiple path does not guarantee an improvement
   of both the reliability and the total capacity).  We propose an
   illustration for this scenario in Figure 5.  This use-case is
   inspired from the Broadband Access via Integrated Terrestrial



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   Satellite Systems (BATS) project and has been published as an ETSI
   Technical Report [ETSITR2017].  This kind of architecture is also
   discussed in the TCPM working group [I-D.ietf-tcpm-converters].

   To cope with packet loss (due to either end-user mobility or
   physical-layer impairments), coding could be introduced in both the
   CPE and at the concentrator.

  -{}- : bidirectional link

                               +-----+    +----------------+
                          +-{}-| SAT |-{}-| BACKBONE       |
  +------+    +------+    |    +-----+    | +------------+ |
  | End  |-{}-| CPE  |-{}-|               | |CONCENTRATOR| |
  | User |    |      |    |    +-----+    | +------------+ |    +------+
  +------+    +------+    |-{}-| DSL |-{}-|                |-{}-|Data  |
                          |    +-----+    |                |    |Server|
                          |               |                |    +------+
                          |    +-----+    |                |
                          +-{}-| LTE |-{}-|                |
                               +-----+    +----------------+

       Figure 5: Network architecture for an hybrid access using NC

4.4.  Dealing with varying capacity

   This use-case considers the usage of coding to cope with cases where
   channel condition can change in less than a second and where the
   physical-layer codes could not guarantee a Quasi-Error-Free (QEF)
   transmission.

   The architecture is recalled in Figure 6.  In these cases, Adaptative
   Coding and Modulation (ACM) may not adapt the modulation and coding
   accordingly and remaining errors could be recovered with higher
   layers redundancy packets.  The coding schemes could be applied at
   the access gateway or the network function block levels to increase
   the reliability of the transmission.  Coding may be applied on IP
   packets or on layer-2 proprietary format packets.

   This use-case is mostly relevant for when mobile users are considered
   or when the chosen band induce a required physical-layer coding that
   may change over time (Q/V bands, Ka band, etc.).  Depending on the
   use-case (e.g. very high frequency bands, mobile users) or depending
   on the deployment use-cases (e.g. performance of the network between
   each individual block), the relevance of adding coding is different.






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   -{}- : bidirectional link

   +---------+    +---+    +--------+    +-------+    +--------+
   |Satellite|    |SAT|    |Physical|    |Access |    |Network |
   |Terminal |-{}-|   |-{}-|Gateway |-{}-|Gateway|-{}-|Function|
   +---------+    +---+    +--------+    +-------+    +--------+
        NC                      NC           NC          NC

       Figure 6: Network architecture for dealing with varying link
                          characteristics with NC

4.5.  Improving the gateway handovers

   This use-case considers the recovery of packets that may be lost
   during gateway handovers.  Whether this is for off-loading one given
   equipment or because the transmission quality is not the same on each
   gateway, changing the transmission gateway may be relevant.  However,
   if gateways are not properly synchronized, this may result in packet
   loss.  During these critical phases, coding can be added to improve
   the reliability of the transmission and allow a seamless gateway
   handover.  Coding could be applied at either the access gateway or
   the network function block.  The control plane manager is in charge
   of taking the decision to change the communication gateway and the
   consequent routes.

   Figure 7 illustrates this use-case.  Depending on the ground
   architecture [I-D.chin-nfvrg-cloud-5g-core-structure-yang] [SAT2017],
   some equipment might be communalised.























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   -{}- : bidirectional link
   !   : management interface
                                          NC            NC
                         +--------+    +-------+    +--------+
                         |Physical|    |Access |    |Network |
                    +-{}-|gateway |-{}-|gateway|-{}-|function|
                    |    +--------+    +-------+    +--------+
                    |                        !       !
   +---------+    +---+              +---------------+
   |Satellite|    |SAT|              | Control plane |
   |Terminal |-{}-|   |              | manager       |
   +---------+    +---+              +---------------+
                    |                        !       !
                    |    +--------+    +-------+    +--------+
                    +-{}-|Physical|-{}-|Access |-{}-|Network |
                         |gateway |    |gateway|    |function|
                         +--------+    +-------+    +--------+
                                          NC            NC

     Figure 7: Network architecture for dealing with gateway handover
                              schemes with NC

5.  Research challenges

5.1.  Towards an increased deployability in SATCOM systems

   SATCOM systems typically feature Performance Enhancement Proxy (PEP)
   RFC 3135 [RFC3135].  PEP usually split TCP end-to-end connections and
   forward TCP packets to the satellite baseband gateway that deals with
   layer-2 and layer-1 encapsulations.  PEP could host coding mechanisms
   and thus support the use-cases that have been discussed in this
   document.

   Deploying coding schemes at the TCP level in these equipment could be
   relevant and independent from the specific characteristics of a
   SATCOM link.  However, there is a research issue in the recurrent
   trade-off in SATCOM systems: how much overhead from redundant
   reliability packets can be introduced to guarantee a better end-user
   QoE while optimizing capacity usage ?

5.2.  Interaction with virtualization

   Related to the foreseen virtualized network infrastructure, coding
   schemes could be easily deployed as VNF.  Next generation of SATCOM
   ground segments could rely on a virtualized environment.  This trend
   can also be seen in cellular networks, making these discussions
   extendable to other deployment scenarios
   [I-D.chin-nfvrg-cloud-5g-core-structure-yang].  As one example, the



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   coding VNF functions deployment in a virtualized environment is
   presented in [I-D.vazquez-nfvrg-netcod-function-virtualization].

   A research challenge would be the optimization of the NFV service
   function chaining, considering a virtualized infrastructure and other
   SATCOM specific functions, to guarantee an efficient radio usage and
   easy-to-deploy SATCOM services.

5.3.  Delay/Disruption Tolerant Networks

   In the context of the deep-space communications, establishing
   communications from terrestrial gateways to satellite platforms can
   be a challenge.  Reliable end-to-end (E2E) communications over such
   links must cope with long delay and frequent link disruptions.
   Delay/Disruption Tolerant Networking [RFC4838] is a solution to
   enable reliable internetworking space communications where both
   standard ad-hoc routing and E2E Internet protocols cannot be used.
   Moreover, DTN can also be seen as an alternative solution to transfer
   the data between a central PEP and a remote PEP.

   Coding enables E2E reliable communication over DTN with adaptive re-
   encoding, as proposed in [THAI15].  In this case, the use-cases
   proposed in Section 4.4 would legitimate the usage of coding within
   the DTN stack to improve the channel utilization and the E2E
   transmission delay.  In this context, the use of erasure coding
   inside a Consultative Committee for Space Data Systems (CCSDS)
   architecture has been specified in [CCSDS-131.5-O-1].  A research
   challenge would be on how such coding can be integrated in the IETF
   DTN stack.

6.  Conclusion

   This document discuses some opportunities to introduce these
   techniques at a wider scale in satellite telecommunications systems.

   Even though this document focuses on satellite systems, it is worth
   pointing out that the some scenarios proposed may be relevant to
   other wireless telecommunication systems.  As one example, the
   generic architecture proposed in Figure 1 may be mapped to cellular
   networks as follows: the 'network function' block gather some of the
   functions of the Evolved Packet Core subsystem, while the 'access
   gateway' and 'physical gateway' blocks gather the same type of
   functions as the Universal Mobile Terrestrial Radio Access Network.
   This mapping extends the opportunities identified in this draft since
   they may be also relevant for cellular networks.






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7.  Acknowledgements

   Many thanks to Tomaso de Cola, Vincent Roca, Lloyd Wood and Marie-
   Jose Montpetit for their help in writing this document.

8.  IANA Considerations

   This memo includes no request to IANA.

9.  Security Considerations

   Security considerations are inherent to any access network.  SATCOM
   systems introduce standard security mechanisms.  On the specific
   scenario of NC in SATCOM systems, there are no specific security
   considerations.

10.  Informative References

   [ASMS2010]
              De Cola, T. and et. al., "Demonstration at opening session
              of ASMS 2010", ASMS , 2010.

   [CCSDS-131.5-O-1]
              CCSDS, "Erasure correcting codes for use in near-earth and
              deep-space communications", CCSDS Experimental
              specification 131.5-0-1, 2014.

   [ETSITR2017]
              "Satellite Earth Stations and Systems (SES); Multi-link
              routing scheme in hybrid access network with heterogeneous
              links", ETSI TR 103 351, 2017.

   [I-D.chin-nfvrg-cloud-5g-core-structure-yang]
              Chen, C. and Z. Pan, "Yang Data Model for Cloud Native 5G
              Core structure", draft-chin-nfvrg-cloud-5g-core-structure-
              yang-00 (work in progress), December 2017.

   [I-D.ietf-tcpm-converters]
              Bonaventure, O., Boucadair, M., Gundavelli, S., and S.
              Seo, "0-RTT TCP Convert Protocol", draft-ietf-tcpm-
              converters-04 (work in progress), October 2018.

   [I-D.vazquez-nfvrg-netcod-function-virtualization]
              Vazquez-Castro, M., Do-Duy, T., Romano, S., and A. Tulino,
              "Network Coding Function Virtualization", draft-vazquez-
              nfvrg-netcod-function-virtualization-02 (work in
              progress), November 2017.




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   [RFC3135]  Border, J., Kojo, M., Griner, J., Montenegro, G., and Z.
              Shelby, "Performance Enhancing Proxies Intended to
              Mitigate Link-Related Degradations", RFC 3135,
              DOI 10.17487/RFC3135, June 2001,
              <https://www.rfc-editor.org/info/rfc3135>.

   [RFC4838]  Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
              R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
              Networking Architecture", RFC 4838, DOI 10.17487/RFC4838,
              April 2007, <https://www.rfc-editor.org/info/rfc4838>.

   [RFC5326]  Ramadas, M., Burleigh, S., and S. Farrell, "Licklider
              Transmission Protocol - Specification", RFC 5326,
              DOI 10.17487/RFC5326, September 2008,
              <https://www.rfc-editor.org/info/rfc5326>.

   [RFC5740]  Adamson, B., Bormann, C., Handley, M., and J. Macker,
              "NACK-Oriented Reliable Multicast (NORM) Transport
              Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009,
              <https://www.rfc-editor.org/info/rfc5740>.

   [RFC6726]  Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen,
              "FLUTE - File Delivery over Unidirectional Transport",
              RFC 6726, DOI 10.17487/RFC6726, November 2012,
              <https://www.rfc-editor.org/info/rfc6726>.

   [RFC8406]  Adamson, B., Adjih, C., Bilbao, J., Firoiu, V., Fitzek,
              F., Ghanem, S., Lochin, E., Masucci, A., Montpetit, M-J.,
              Pedersen, M., Peralta, G., Roca, V., Ed., Saxena, P., and
              S. Sivakumar, "Taxonomy of Coding Techniques for Efficient
              Network Communications", RFC 8406, DOI 10.17487/RFC8406,
              June 2018, <https://www.rfc-editor.org/info/rfc8406>.

   [SAT2017]  Ahmed, T., Dubois, E., Dupe, JB., Ferrus, R., Gelard, P.,
              and N. Kuhn, "Software-defined satellite cloud RAN", Int.
              J. Satell. Commun. Network. vol. 36, 2017.

   [SHINE]    Pietro Romano, S. and et. al., "Secure Hybrid In Network
              caching Environment (SHINE) ESA project", ESA project ,
              2017 on-going.

   [THAI15]   Thai, T., Chaganti, V., Lochin, E., Lacan, J., Dubois, E.,
              and P. Gelard, "Enabling E2E reliable communications with
              adaptive re-encoding over delay tolerant networks",
              Proceedings of the IEEE International Conference on
              Communications , June 2015.





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Internet-Draft        Network coding and satellites             Jan 2019


Authors' Addresses

   Nicolas Kuhn (editor)
   CNES
   18 Avenue Edouard Belin
   Toulouse  31400
   France

   Email: nicolas.kuhn@cnes.fr


   Emmanuel Lochin (editor)
   ISAE-SUPAERO
   10 Avenue Edouard Belin
   Toulouse  31400
   France

   Email: emmanuel.lochin@isae-supaero.fr

































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